Helmet

ABSTRACT

A helmet, comprising an outer shell; a head mount, configured to be mounted on the top of the head of a wearer of the helmet; wherein the head mount is suspended within the outer shell such that, in use, an air gap is provided between head mount and the outer shell; the helmet further comprises a head engagement device that is mounted on a surface of the head mount, that is configured to face the head of a wearer of the helmet, such that the head engagement device can move relative to the head mount; and a low friction interface is provided between the head mount and the head engagement device.

The present invention relates to helmets.

Helmets are known for use in various activities. These activities include combat and industrial purposes, such as protective helmets for soldiers and hard-hats or helmets used by builders, mine-workers, or operators of industrial machinery for example. Helmets are also common in sporting activities. For example, protective helmets may be used in ice hockey, cycling, motorcycling, motor-car racing, skiing, snow-boarding, skating, skateboarding, equestrian activities, American football, baseball, rugby, soccer, cricket, lacrosse, climbing, golf, airsoft, roller derby and paintballing.

Helmets can be of fixed size or adjustable, to fit different sizes and shapes of head. In some types of helmet, e.g. commonly in ice-hockey helmets, the adjustability can be provided by moving parts of the helmet to change the outer and inner dimensions of the helmet. This can be achieved by having a helmet with two or more parts which can move with respect to each other. In other cases, e.g. commonly in cycling helmets, the helmet is provided with an attachment device for fixing the helmet to the user's head, and it is the attachment device that can vary in dimension to fit the user's head whilst the main body or shell of the helmet remains the same size. In some cases, comfort padding within the helmet can act as the attachment device. The attachment device can also be provided in the form of a plurality of physically separate parts, for example a plurality of comfort pads which are not interconnected with each other. Such attachment devices for seating the helmet on a user's head may be used together with additional strapping (such as a chin strap) to further secure the helmet in place. Combinations of these adjustment mechanisms are also possible.

Helmets are often made of an outer shell, that is usually hard and made of a plastic or a composite material, and an energy absorbing layer, often referred to as a liner. In other arrangements, such as a rugby scrum cap, a helmet may have no hard outer shell, and the helmet as a whole may be flexible. In any case, nowadays, a protective helmet has to be designed so as to satisfy certain legal requirements which relate to inter alia the maximum acceleration that may occur in the centre of gravity of the brain at a specified load. Typically, tests are performed, in which what is known as a dummy skull equipped with a helmet is subjected to a radial blow towards the head. This has resulted in modern helmets having good energy- absorption capacity in the case of blows radially against the skull. Progress has also been made (e.g. WO 2001/045526 and WO 2011/139224, which are both incorporated herein by reference, in their entireties) in developing helmets to lessen the energy transmitted from oblique blows (i.e. which combine both tangential and radial components), by absorbing or dissipating rotation energy and/or redirecting it into translational energy rather than rotational energy.

Such oblique impacts (in the absence of protection) result in both translational acceleration and angular acceleration of the brain. Angular acceleration causes the brain to rotate within the skull creating injuries on bodily elements connecting the brain to the skull and also to the brain itself.

Examples of rotational injuries include Mild Traumatic Brain Injuries (MTBI) such as concussion, and Severe Traumatic Brain Injuries (STBI) such as subdural haematomas (SDH), bleeding as a consequence of blood vessels rapturing, and diffuse axonal injuries (DAI), which can be summarized as nerve fibres being over stretched as a consequence of high shear deformations in the brain tissue.

Depending on the characteristics of the rotational force, such as the duration, amplitude and rate of increase, either concussion, SDH, DAI or a combination of these injuries can be suffered. Generally speaking, SDH occur in the case of accelerations of short duration and great amplitude, while DAI occur in the case of longer and more widespread acceleration loads.

In helmets such as those disclosed in WO 2001/045526 and WO 2011/139224 that may reduce the rotational energy transmitted to the brain caused by oblique impacts, two parts of the helmet may be configured to slide relative to each other at a sliding interface following an oblique impact.

In some helmets a head attachment device is suspended within, and separated from, a hard outer shell. Such helmets may be simple and cheap to manufacture and provide sufficient protection from radial impacts for certain helmet uses. However, it may be desirable to improve the performance of such helmets, for example in the event of an oblique impact, preferably without substantially increasing the manufacturing costs and/or effort.

According to an aspect of the disclosure there is provided a helmet, comprising:

-   -   an outer shell;     -   a head mount, configured to be mounted on the top of the head of         a wearer of the helmet;     -   wherein the head mount is suspended within the outer shell such         that, in use, an air gap is provided between head mount and the         outer shell;     -   the helmet further comprises a head engagement device that is         mounted on a surface of the head mount, that is configured to         face the head of a wearer of the helmet, such that the head         engagement device can move relative to the head mount; and     -   a low friction interface is provided between the head mount and         the head engagement device.

In an arrangement, the head engagement device is connected to the head mount.

In an arrangement, the head mount comprises a plurality of straps that are configured to extend across the top of the head of a wearer of the helmet and are connected to connection points on the outer shell.

In an arrangement, the head mount comprises a plurality of straps that extend between an opposing pair of connection points.

In an arrangement, at least two straps are connected to each other.

In an arrangement, the head engagement device is connected to the head mount by at least one connector that engages with one of the straps.

In an arrangement, the at least one connector has a first end and a second end that are both joined to the head engagement device at respective first and second locations on the head engagement device; and a strap is located between the connector and the head engagement device in a region between the first and second locations on the head engagement device.

In an arrangement, the strap is not fixedly secured to any part of the connector such that the strap can slide relative to the connector.

In an arrangement, the connector is formed from an elongate section of material, optionally one of a cord, band or a tape.

In an arrangement, plural connectors are formed from separate pieces of said material.

In an arrangement, plural connectors are formed from sections of a single piece of said material.

In an arrangement, the head mount comprises at least one strap connected to the front of the outer shell extending in a direction towards the rear of the helmet.

In an arrangement, the head engagement device is provided as a single component.

In an arrangement, the head engagement device is formed from plural separate sections.

In an arrangement, the head mount comprises a head ring that is configured to engage at least the forehead of a wearer of the helmet; and

-   -   the head engagement device comprises a crown region that is         configured to be located between the top of the head of a wearer         of the helmet and the head mount, and a frontal region that is         configured to be located adjacent the head ring.

In an arrangement, the head engagement device further comprises an intermediate region that connects the crown region to the frontal region.

In an arrangement, the frontal regional of the head engagement device is located between the forehead of the wearer of the helmet and the head ring.

In an arrangement, the head ring is located between the forehead of the wearer of the helmet and the frontal regional of the head engagement device.

In an arrangement, the helmet further comprises a front pad positioned to be adjacent the forehead of the wearer of the helmet.

In an arrangement, the front pad is connected to at least one of the head ring, the frontal region of the head engagement device and the outer shell.

In an arrangement, the front pad is connected by elastic connectors that are configured to enable the front pad to move relative to the component to which it is connected.

In an arrangement, the head engagement device comprises one or more pads provided on a surface of the head engagement device facing the head of a wearer of the helmet.

In an arrangement, the head engagement device comprises a plate of material, optionally shaped to conform to the head of a wearer of the helmet.

In an arrangement, the head engagement device comprises a plurality of holes that may be configured to provide at least one of a location for a connector to join to the head engagement device and ventilation.

In an arrangement, the low friction interface is provided by a low coefficient of friction between the surfaces of the head mount and the head engagement.

In an arrangement, in the absence of an impact on the helmet, the separation between the outer shell and the head mount at a location corresponding to the top of the head of a wearer provided by the air gap is at least 10 mm, optionally at least 15 mm, optionally at least 20 mm, optionally at least 30 mm, optionally at least 40 mm.

The invention is described in detail below, with reference to the accompanying figures, in which:

FIG. 1 depicts a cross-section through a helmet for providing protection against oblique impacts;

FIG. 2 is a diagram showing the functioning principle of the helmet of FIG. 1 ;

FIGS. 3A, 3B & 3C show variations of the structure of the helmet of FIG. 1 ;

FIGS. 4 and 5 schematically depict another arrangement of a helmet;

FIG. 6 schematically depicts, in a cross-section, another arrangement of a helmet;

FIG. 7 depicts the inside of an example of a helmet according to the arrangement depicted in FIG. 6 ;

FIGS. 8, 9 and 10 depict a connector for use in a helmet of the arrangement depicted in FIG. 7 ;

FIG. 11 depicts the inside of a further example of a helmet;

FIG. 12 depicts the inside of a further example of a helmet;

FIG. 13 depicts the inside of a further example of a helmet;

FIG. 14 depicts the inside of a further example of a helmet; and

FIG. 15 depicts the helmet of FIG. 14 from the side.

The proportions of the thicknesses of the various layers in the helmets depicted in the figures have been exaggerated in the drawings for the sake of clarity and can of course be adapted according to need and requirements.

FIG. 1 depicts a first helmet 1 of the sort discussed in WO 01/45526, intended for providing protection against oblique impacts. This type of helmet could be any of the types of helmet discussed above.

Protective helmet 1 is constructed with an outer shell 2 and, arranged inside the outer shell 2, an inner shell 3 that is intended for contact with the head of the wearer.

Arranged between the outer shell 2 and the inner shell 3 is a sliding layer 4 (also called a sliding facilitator or low friction layer), which may enable displacement between the outer shell 2 and the inner shell 3. In particular, as discussed below, a sliding layer 4 or sliding facilitator may be configured such that sliding may occur between two parts during an impact. For example, it may be configured to enable sliding under forces associated with an impact on the helmet 1 that is expected to be survivable for the wearer of the helmet 1. In some arrangements, it may be desirable to configure the sliding layer 4 such that the coefficient of friction is between 0.001 and 0.3 and/or below 0.15.

Arranged in the edge portion of the helmet 1, in the FIG. 1 depiction, may be one or more connecting members 5 which interconnect the outer shell 2 and the inner shell 3. In some arrangements, the connectors may counteract mutual displacement between the outer shell 2 and the inner shell 3 by absorbing energy. However, this is not essential. Further, even where this feature is present, the amount of energy absorbed is usually minimal in comparison to the energy absorbed by the inner shell 3 during an impact. In other arrangements, connecting members 5 may not be present at all.

Further, the location of these connecting members 5 can be varied (for example, being positioned away from the edge portion, and connecting the outer shell 2 and the inner shell 3 through the sliding layer 4).

The outer shell 2 is preferably relatively thin and strong so as to withstand impact of various types. The outer shell 2 could be made of a polymer material such as polycarbonate (PC), polyvinylchloride (PVC) or acrylonitrile butadiene styrene (ABS) for example. Advantageously, the polymer material can be fibre-reinforced, using materials such as glass-fibre, Aramid, Twaron, carbon-fibre or Kevlar.

The inner shell 3 is considerably thicker and acts as an energy absorbing layer. As such, it is capable of damping or absorbing impacts against the head. It can advantageously be made of foam material like expanded polystyrene (EPS), expanded polypropylene (EPP), expanded polyurethane (EPU), vinyl nitrile foam; or other materials forming a honeycomb-like structure, for example; or strain rate sensitive foams such as marketed under the brand-names Poron™ and D3O™. The construction can be varied in different ways, which emerge below, with, for example, a number of layers of different materials.

Inner shell 3 is designed for absorbing the energy of an impact. Other elements of the helmet 1 will absorb that energy to a limited extent (e.g. the hard outer shell 2 or so-called ‘comfort padding’ provided within the inner shell 3), but that is not their primary purpose and their contribution to the energy absorption is minimal compared to the energy absorption of the inner shell 3. Indeed, although some other elements such as comfort padding may be made of ‘compressible’ materials, and as such considered as ‘energy absorbing’ in other contexts, it is well recognised in the field of helmets that compressible materials are not necessarily ‘energy absorbing’ in the sense of absorbing a meaningful amount of energy during an impact, for the purposes of reducing the harm to the wearer of the helmet.

A number of different materials and embodiments can be used as the sliding layer 4 or sliding facilitator, for example oil, Teflon, microspheres, air, rubber, polycarbonate (PC), a fabric material such as felt, etc. Such a layer may have a thickness of roughly 0.1-5 mm, but other thicknesses can also be used, depending on the material selected and the performance desired. The number of sliding layers and their positioning can also be varied, and an example of this is discussed below (with reference to FIG. 3 b ).

As connecting members 5, use can be made of, for example, deformable strips of plastic or metal which are anchored in the outer shell and the inner shell in a suitable manner.

FIG. 2 shows the functioning principle of protective helmet 1, in which the helmet 1 and a skull 10 of a wearer are assumed to be semi-cylindrical, with the skull 10 being mounted on a longitudinal axis 11. Torsional force and torque are transmitted to the skull 10 when the helmet 1 is subjected to an oblique impact K. The impact force K gives rise to both a tangential force K_(T) and a radial force K_(R) against the protective helmet 1. In this particular context, only the helmet-rotating tangential force K_(T) and its effect are of interest.

As can be seen, the force K gives rise to a displacement 12 of the outer shell 2 relative to the inner shell 3, the connecting members 5 being deformed. Significant reductions in the torsional force transmitted to the skull 10 can be obtained with such an arrangement. A typical reduction may be roughly 25% but reductions as high as 90% may be possible in some instances. This is a result of the sliding motion between the inner shell 3 and the outer shell 2 reducing the amount of energy which is transferred into radial acceleration.

Sliding motion can also occur in the circumferential direction of the protective helmet 1, although this is not depicted. This can be as a consequence of circumferential angular rotation between the outer shell 2 and the inner shell 3 (i.e. during an impact the outer shell 2 can be rotated by a circumferential angle relative to the inner shell 3).

Other arrangements of the protective helmet 1 are also possible. A few possible variants are shown in FIG. 3 . In FIG. 3 a , the inner shell 3 is constructed from a relatively thin outer layer 3″ and a relatively thick inner layer 3′. The outer layer 3″ is preferably harder than the inner layer 3′, to help facilitate the sliding with respect to outer shell 2. In FIG. 3 b , the inner shell 3 is constructed in the same manner as in FIG. 3 a . In this case, however, there are two sliding layers 4, between which there is an intermediate shell 6. The two sliding layers 4 can, if so desired, be embodied differently and made of different materials. One possibility, for example, is to have lower friction in the outer sliding layer than in the inner. In FIG. 3 c , the outer shell 2 is embodied differently from previously. In this case, a harder outer layer 2″ covers a softer inner layer 2′. The inner layer 2′ may, for example, be the same material as the inner shell 3.

FIG. 4 depicts a second helmet 1 of the sort discussed in WO 2011/139224, which is also intended for providing protection against oblique impacts. This type of helmet could also be any of the types of helmet discussed above.

In FIG. 4 , helmet 1 comprises an energy absorbing layer 3, similar to the inner shell 3 of the helmet of FIG. 1 . The outer surface of the energy absorbing layer 3 may be provided from the same material as the energy absorbing layer 3 (i.e. there may be no additional outer shell), or the outer surface could be a rigid shell 2 (see FIG. 5 ) equivalent to the outer shell 2 of the helmet shown in FIG. 1 . In that case, the rigid shell 2 may be made from a different material than the energy absorbing layer 3. The helmet 1 of FIG. 4 has a plurality of vents 7, which are optional, extending through both the energy absorbing layer 3 and the outer shell 2, thereby allowing airflow through the helmet 1.

An interface layer 13 (also called an attachment device) is provided, to interface with (and/or attach helmet 1 to) a wearer's head. As previously discussed, this may be desirable when energy absorbing layer 3 and rigid shell 2 cannot be adjusted in size, as it allows for the different size heads to be accommodated by adjusting the size of the attachment device 13. The attachment device 13 could be made of an elastic or semi-elastic polymer material, such as PC, ABS, PVC or PTFE, or a natural fibre material such as cotton cloth. For example, a cap of textile or a net could form the attachment device 13.

Although the attachment device 13 is shown as comprising a headband portion with further strap portions extending from the front, back, left and right sides, the particular configuration of the attachment device 13 can vary according to the configuration of the helmet. In some cases the attachment device may be more like a continuous (shaped) sheet, perhaps with holes or gaps, e.g. corresponding to the positions of vents 7, to allow air-flow through the helmet.

FIG. 4 also depicts an optional adjustment device 6 for adjusting the diameter of the head band of the attachment device 13 for the particular wearer. In other arrangements, the head band could be an elastic head band in which case the adjustment device 6 could be excluded.

A sliding facilitator 4 is provided radially inwards of the energy absorbing layer 3. The sliding facilitator 4 is adapted to slide against the energy absorbing layer or against the attachment device 13 that is provided for attaching the helmet to a wearer's head.

The sliding facilitator 4 is provided to assist sliding of the energy absorbing layer 3 in relation to an attachment device 13, in the same manner as discussed above. The sliding facilitator 4 may be a material having a low coefficient of friction, or may be coated with such a material.

As such, in the FIG. 4 helmet, the sliding facilitator 8 may be provided on or integrated with the innermost side of the energy absorbing layer 3, facing the attachment device 13.

However, it is equally conceivable that the sliding facilitator 4 may be provided on or integrated with the outer surface of the attachment device 13, for the same purpose of providing slidability between the energy absorbing layer 3 and the attachment device 13. That is, in particular arrangements, the attachment device 13 itself can be adapted to act as a sliding facilitator 4 and may comprise a low friction material.

In other words, the sliding facilitator 4 is provided radially inwards of the energy absorbing layer 3. The sliding facilitator can also be provided radially outwards of the attachment device 13.

When the attachment device 13 is formed as a cap or net (as discussed above), sliding facilitators 4 may be provided as patches of low friction material.

The low friction material may be a waxy polymer, such as PTFE, ABS, PVC, PC, Nylon, PFA, EEP, PE and UHMWPE, or a powder material which could be infused with a lubricant. The low friction material could be a fabric material. As discussed, this low friction material could be applied to either one, or both of the sliding facilitator and the energy absorbing layer.

The attachment device 13 can be fixed to the energy absorbing layer 3 and/or the outer shell 2 by means of fixing members 5, such as the four fixing members 5 a, 5 b, 5 c and 5 d in FIG. 4 . These may be adapted to absorb energy by deforming in an elastic, semi-elastic or plastic way. However, this is not essential. Further, even where this feature is present, the amount of energy absorbed is usually minimal in comparison to the energy absorbed by the energy absorbing layer 3 during an impact.

According to the arrangement shown in FIG. 4 the four fixing members 5 a, 5 b, 5 c and 5 d are suspension members 5 a, 5 b, 5 c, 5 d, having first and second portions 8, 9, wherein the first portions 8 of the suspension members 5 a, 5 b, 5 c, 5 d are adapted to be fixed to the attachment device 13, and the second portions 9 of the suspension members 5 a, 5 b, 5 c, 5 d are adapted to be fixed to the energy absorbing layer 3.

FIG. 5 shows an arrangement of a helmet similar to the helmet in FIG. 4 , when placed on a wearer's head. The helmet 1 of FIG. 5 comprises a hard outer shell 2 made from a different material than the energy absorbing layer 3. In contrast to FIG. 4 , in FIG. 5 the attachment device 13 is fixed to the energy absorbing layer 3 by means of two fixing members 5 a, 5 b, which are adapted to absorb energy and forces elastically, semi-elastically or plastically.

A frontal oblique impact I creating a rotational force to the helmet is shown in FIG. 5 . The oblique impact I causes the energy absorbing layer 3 to slide in relation to the attachment device 13. The attachment device 13 is fixed to the energy absorbing layer 3 by means of the fixing members 5 a, 5 b. Although only two such fixing members are shown, for the sake of clarity, in practice many such fixing members may be present. The fixing members 5 can absorb the rotational forces by deforming elastically or semi-elastically. In other arrangements, the deformation may be plastic, even resulting in the severing of one or more of the fixing members 5. In the case of plastic deformation, at least the fixing members 5 will need to be replaced after an impact. In some case a combination of plastic and elastic deformation in the fixing members 5 may occur, i.e. some fixing members 5 rupture, absorbing energy plastically, whilst other fixing members deform and absorb forces elastically.

In general, in the helmets of FIG. 4 and FIG. 5 , during an impact the energy absorbing layer 3 acts as an impact absorber by compressing, in the same way as the inner shell of the FIG. 1 helmet. If an outer shell 2 is used, it will help spread out the impact energy over the energy absorbing layer 3. The sliding facilitator 4 will also allow sliding between the attachment device and the energy absorbing layer. This allows for a controlled way to dissipate energy that would otherwise be transmitted as rotational energy to the brain. The energy can be dissipated by friction heat, energy absorbing layer deformation or deformation or displacement of the fixing members. The reduced energy transmission results in reduced rotational acceleration affecting the brain, thus reducing the rotation of the brain within the skull. The risk of rotational injuries including MTBI and STBI such as subdural haematomas, SDH, blood vessel rapturing, concussions and DAI is thereby reduced.

FIG. 6 schematically depicts a cross-section a helmet of a different type from that depicted in FIGS. 1 to 5 . In a helmet 1 such as that depicted in FIG. 6 , a head mount 20 is suspended within an outer shell 2 such that an air gap 21 is provided between the outer shell 2 and the head mount 20. The head mount 20 may be connected to the outer shell 2 by connectors 25. Helmets of this type are commonly used for industrial purposes, such as by builders, mine-workers or operators of industrial machinery. However, helmets based on such an arrangement may be used for other purposes. In some uses, the outer shell 2 may be a hard shell made of a polymer material such as polycarbonate (PC), polyvinylchloride (PVC), high density polyethylene (HDPE) or acrylonitrile butadiene styrene (ABS) for example. Advantageously, the polymer material can be fibre-reinforced, using materials such as glass-fibre, Aramid, Twaron, carbon-fibre or Kevlar.

Although the following disclosure relates to an example of a helmet 1 in which the outer shell 2 is formed solely from a hard shell, it should be appreciated that the disclosed arrangement may be applicable to other helmet configurations. For example, the outer shell may alternatively or additionally include a layer of energy absorbing material. Such an energy absorbing material may be made, for example, of a foam material like expanded polystyrene (EPS), expanded polypropylene (EPP), expanded polyurethane (EPU), vinyl nitrile foam; or other materials forming a honeycomb-like structure, or strain rate sensitive foams such as marketed under the brand-names Poron™ and D3O™.

Where used, the layer of energy absorbing material may be provided as a shell over substantially all of the surface of the hard shell facing the wearer's head, although ventilation holes may be provided. Alternatively or additionally, localised regions of energy absorbing material may be provided between the hard shell and the head mount. For example, a band of energy absorbing material may be provided around the lower edge of the hard shell and/or a section of energy absorbing material may be provided to be located above the top of the wearer's head.

In a helmet such as that depicted in FIG. 6 , the provision of an air gap 21 between the inner surface of the outer shell 2 and the head mount 20 is intended to ensure that loading caused by an impact on the outer shell 2 is spread across a wearer's head. In particular, the load is not localised on a point on the wearer's head adjacent the point of impact on the helmet 1. Instead, the load is spread across the outer shell 2 and, subsequently, spread across the head mount 20 and therefore spread across the wearer's skull.

During such an impact, the energy of the impact may be absorbed by deformation of parts of the helmet, such as the head mount, reducing the size of the air gap.

Accordingly, the size of the air gap 21 between the outer shell 2 and the head mount 20 may be chosen to ensure that, under an impact on the helmet that the helmet is designed to withstand, the head mount 20 does not come into contact with the outer shell 2, namely the air gap 21 is not entirely eliminated such that the impact may be directly transferred from the hard shell to the head mount.

In an arrangement, the helmet 1 may be configured such that, in the absence of an impact on the helmet, the separation between the outer shell 2 and the head mount 20 at a location corresponding to the top of the head of a wearer is at least 10 mm, optionally at least 15 mm, optionally at least 20 mm, optionally at least 30 mm, optionally at least 40 mm. The magnitude of the impact that the helmet 1 is designed to withstand, and therefore the size of the air gap 21, may depend upon the intended use of the helmet 1. It should be understood that, depending on the intended use of the helmet the size of the air gap 21 may be different at different locations. For example, the air gap 21 may be smaller at the front, back or side of the helmet than it is at the location corresponding to the top of the head of the wearer.

In helmet arrangements that include energy absorbing material, the energy absorbing material may contribute to the helmet's ability to withstand radial impacts. In particular in arrangements in which the energy absorbing material is located within the air gap between the outer shell 2 and the head mount 20 at the location corresponding to the top of the wearer's head, it will be appreciated that the gap between the head mount and the surface of the energy absorbing layer will be smaller than the gap between the outer shell and the head mount, and may be eliminated altogether. Additionally, as a result of the energy absorbing material's contribution in the event of a radial impact, a smaller gap between the outer shell and the head mount may be required than would be the case in the absence of the energy absorbing material.

The head mount 20 may be provided in any form that may conform to the head of a wearer, or at least the top of their head, and mount the helmet to the wearer's head or function to contribute to mounting the helmet to the wearer's head. In some configurations, it may assist in securing the helmet 1 to the wearer's head but this is not essential. In some arrangements, the head mount 20 may include a head band, or head ring, that at least partially surrounds the wearer's head. Alternatively or additionally, the head mount 20 may include one or more straps that extend across the top of the wearer's head. Alternatively or additionally, the head mount 20 may include a cap or shell that encapsulates an upper portion of the wearer's head. Straps or bands that form part of the head mount may be formed from Nylon. Other materials may alternatively or additionally be used.

FIG. 7 depicts an arrangement in which a helmet of the type schematically depicted in FIG. 6 has features in accordance with the present disclosure. As shown, the head mount includes a plurality of straps 20 that extend across the top of the head of a wearer of the helmet. The straps 20 may be connected at connection points to the outer shell 2 by any of a plurality of known methods. For example, the outer shell 2 may be moulded to include sockets into which connectors 25 may be inserted.

In the arrangement depicted in FIG. 7 , the head mount is formed from two straps 20 that each extend between a pair of connectors 25 positioned such that the straps 20 extend across the head of the wearer of the helmet. For example, a first strap 20 may extend from a rear left position to a forward right position and a second strap 20 may extend from a rear right position to a forward left position. However, it should be appreciated that many other arrangements may be used. For example, additional straps may be provided, for example, such that there are three, four or more straps extending across the top of the head of the wearer. Similarly, the position of the connection points of the straps 20 to the remainder of the helmet 1 may be different from that depicted in FIG. 7 .

In an arrangement, where different straps 20 are in proximity to each other, for example, at the top of the wearer's head, the straps 20 may not be connected to each other, permitting some movement of one strap relative to another. In other arrangements, the straps may be connected to each other where they cross. In a further arrangement, the head mount may include one or more straps that extend from a connection point to the remainder of the helmet 1 to a point at which it is connected to other straps, for example, at a location corresponding to the top of the head of a wearer of the helmet. Finally, as noted above, in other arrangements, the head mount may be formed from components other than straps, for example from a cap or shell that can be mounted to the top of the head of the wearer of the helmet 1.

As shown in FIG. 7 , the helmet 1 further includes a head engagement device 40.

The head engagement device 40 is mounted on a surface of the head mount, namely the straps 20 in the arrangement depicted in FIG. 7 , that faces the head of a wearer when the wearer is wearing the helmet 1. In other words, the head engagement device 40 is provided on the opposite side of the head mount 20 from the airgap that exists between the head mount 20 and the outer shell 2.

As is discussed in further detail below, the head engagement device 40 is mounted such that the head engagement device 40 can move relative to the head mount 20. In other words, the head engagement device 40 and the head mount 20 are not rigidly connected to each other. The head engagement device 40 may function in the same manner as, or in a similar manner to, an interface layer as discussed above. In the event of an oblique impact on the helmet 1 while it is being worn by a wearer, the ability of the head engagement device 40 to move relative to the head mount 20 enables movement, such as a rotation, of the helmet 1 relative to the wearer's head. This may provide the benefits discussed above, such as reducing injury to the wearer of the helmet from such impacts.

A low friction interface may be provided between the head mount 20 and the head engagement device 40. This may facilitate the movement of the head engagement device 40 relative to the head mount 20 under an impact to the helmet 1.

The low friction interface between the head mount 20 and the head engagement device 40 may be implemented by any method corresponding to those discussed above for other helmet arrangements. For example, the head engagement device 40 may be formed from a material that provides a sufficiently low coefficient friction between it and the head mount 20. For example, it may be formed from polypropylene (PP), Nylon, polycarbonate (PC), a polyketone, or any other low friction material, such as those discussed above. By suitable material selection for forming one or both of the head mount and the head engagement device, the low friction interface may be provided without provision of additional components and/or surface treatments.

In other arrangements, one or both of the surfaces of the head mount 20 and the head engagement device 40, where they are in contact, may be provided with a separate sliding facilitator, such as a patch of low friction material or a coating of another material, which could be another polymer with a low coefficient of friction or a section of a fabric material or felt, or may have a lubricant applied to it.

The head engagement device 40 may be connected to the helmet 1 in any suitable manner that permits movement of the head engagement device 40 relative to the head mount 20. For example, the head engagement device 40 may be connected to the outer shell 2, for example by connecters that permit movement of the head engagement device 40 relative to the outer shell 2. Such connectors may include elastic components that can stretch when movement of the head engagement device 40 relative to the outer shell 2 is required.

In an arrangement, such as that depicted in FIG. 7 , the head engagement device 40 may be connected to the head mount, for example to the one or more straps 20 that is part of the head mount.

Where the head engagement device 40 is connected to the head mount, connectors 45 may be used that permit some movement of the head engagement device 40 relative to the part of the head mount to which it is connected.

In an arrangement, a connector 45 may have first and second ends 46, 47 joined to the head engagement device 40 at respective first and second locations on the head engagement device 40 and positioned such that a strap 20 of the head mount is located between the connector 45 and the head engagement device 40 in a region between the first and second locations on the head engagement device 40. In such an arrangement, the strap 20 may not be fixedly secured to any part of the connector 45 such that the strap can slide in its lengthwise direction and/or sideways relative to the connector 45. However, the head engagement device 40 is restricted from being completely removed from the strap 20.

In such an arrangement, the connector 45 may be formed from a material, or covered with a material, that provides a sufficiently low coefficient of friction between it and the strap 20 that movement of the head engagement device relative to the head mount is not significantly reduced, and therefore does not significantly hinder the function of the helmet 1. Alternatively or additionally, the connector 45 may be formed from an elastic material such that, to the extent that a part of the connector 45 does not slide relative to the strap 20, the strap can move relative to the first and second parts 46, 47 of the connector 45 joined to the head engagement device 40, for example by stretching of the connector,, permitting the desired movement of the head engagement device relative to the head mount.

In an arrangement such as the depicted in FIG. 7 , the connector 45 may be formed from an elongate section of material. For example, the connector 45 may be formed from a section of material in the shape of a cord, band or tape. Such a material may, for example, be generally round or rectangular in cross section. The connector may be formed from an elastic material, which may be beneficial for the function of the connector in the event of an impact on the helmet 1, as described above, and/or may facilitate assembly of the helmet 1. In an arrangement, the connector 45 may be formed from an elastic material that is coated with a layer of fabric. The connector 45 may alternatively or additionally be formed from silicone, rubber or another elastic plastic material.

A connector such as that disused above may be joined to the head engagement device 40 at the first and second locations by any suitable method, including for example adhesive or mechanical methods such as a snap-fit connection. Alternatively two ends of the elongate material may be tied to each other and/or at least one end may be tied to a part of the helmet 1 in order to secure it.

In an arrangement, as schematically depicted in FIGS. 8 to 10 , the length of material 50 used to form the connector 45 may be terminated with a component, such as a relatively short bar 51. The bar 51 is connected to the elongate material 50 such that the length of the bar 51 is at an angle to the elongate length of the material, optionally perpendicular. As shown in FIG. 9 , during assembly, the bar 51 may be inserted in a lengthwise direction through a hole 41 in the head engagement device 40. However, as shown in FIG. 9 , the bar 51 will subsequently naturally orient itself against the surface of the head engagement device 40 such that the bar 51 cannot pass back through the hole. It will be appreciated that in such an arrangement, the hole 41 in the head engagement device 40 may be configured to be larger than the cross-section of the bar 51 but be smaller than the length of the bar 51.

In an arrangement such as that depicted in FIG. 7 , the strap 20 is connected to the head engagement device 40 such that the strap 20 is on the opposite side of the head engagement device 40 from the head of a wearer of the helmet. Accordingly, the connector 45 is also predominantly on the opposite side of the head engagement device 40 from the head of the wearer of a helmet. In a connector arrangement as discussed above and depicted in FIGS. 8 to 10 , the connector 45 may be configured such that the length of material forming the connector 45 extends through a hole 41 in the head engagement device 40 from the side against which the strap 20 is in contact, with the result that the bar 51 is positioned on the surface of the head engagement device 40 facing the head of a wearer of the helmet.

If this is undesirable, for example if it impacts on the comfort of the wearer of the helmet or if it is desirable to conceal the bar 51, either for aesthetic reasons or to reduce the risk of damage to the connector 45 and/or the risk of tampering, a second hole 41 may be provided in the head engagement device 40 at each location used for securing the connector. In such an arrangement, the length of material may pass through one hole from the region in which the connector is engaging with the strap, pass across a section of the head engagement device 40 between the two holes 41, and then pass through the second hole. In such an arrangement, the bar 51 is held on the same side of the head engagement device 40 as the strap 20, namely on the opposite side of the head engagement device 40 form the head of the wearer.

In an arrangement, each connector 45 may be formed from its own separate section of elongate material. Alternatively, one or more connectors 45 may be formed from sections of a single piece of the elongate material. For example, plural connectors 45 may be formed in a manner corresponding to the above but, in place of a bar 51 at a location where the connector 45 joins the head engagement device 40, the elongate material may extend to another connector 45. In an arrangement, all of the connectors 45 used to connect a head engagement device 40 to the head mount may be formed from a single length of elongate material.

As shown in FIG. 7 , in an arrangement where the head mount includes straps 20 that extend across the head of a wearer of the helmet between two connection points on the outer shell 2, a pair of connectors 45 may be provided for each strap 20 on opposite sides of the head engagement device 40. Similarly, at least one connector 45, optionally a pair of connectors 45, may be provided for each strap 20. However, this is not essential. For example, as shown in FIG. 11 , fewer connections may be provided between the head engagement device 40 and the head mount, such as the straps 20. In the arrangement depicted in FIG. 11 , for example, connectors 45 may only be provided at the rear of the helmet 1.

FIG. 12 depicts an alternative arrangement for connecting the head engagement device 40. As shown, the head engagement device 40 may include holes 60 though which a strap 20 that is part of a head mount may pass.

As discussed above, other arrangements for connecting the head engagement device 40 may alternatively or additionally be used. For example, an elastically deformable connector may be provided between the head mount and the head engagement device 40 such that a first part of the connector is secured to a part of the head mount, such as a strap 20, and a second part of the connector is secured to a part of the head engagement device 40. Movement of the head engagement device relative to the head mount may be enabled by stretching and/or other deformation of the connector. Such a connector may be secured to one or both of the surfaces of the head mount and head engagement device that face each other. The connector may be secured to one or both of the head mount and head engagement device by any suitable means, including for example, by means of hook and loop material and/or by adhesive.

As shown in the arrangements depicted in FIGS. 7, 11 and 12 , the head engagement device 40 may be provided as a single component, such as a single layer of material. However, this need not be the case. For example, the head engagement device may be formed from plural separate sections. The separate sections may remain separate and, for example, be separately connected to the head mount and/or other parts of the helmet 1. Alternatively, two or more sections may be connected during assembly of the helmet. In an arrangement, a separate section of the head engagement device may be connected to each of, or a subset of, the straps 20 that form, or are part of, the head mount.

In an arrangement, the head engagement device, or one or more parts of it may be formed by injection moulding or vacuum-forming. It may therefore be formed to have a shape that conforms to the shape of the head of a wearer of the helmet.

In arrangement of a helmet 1, such as depicted in FIG. 7 , the head mount may include a head ring 30 that engages at least the forehead of a wearer of the helmet and may substantially surround the head of the wearer. It should be appreciated that such a head ring 30 may be connected to the helmet 1 separately from the remainder of the head mount, such as straps 20. Alternatively the head ring 30 may be connected to the helmet 1 by means of the straps 20. As a further alternative, the straps 20 may be connected to the rest of the helmet 1 by means of the head ring 30.

In an arrangement in which the helmet 1 includes a head ring 30, the head engagement device 40 may include a crown region 43 that is configured to be located between the top of the head of the wearer of the helmet and the head mount, such as straps 20, and a frontal region 44 that is configured to be located adjacent to the head ring 30, at least in the region of the forehead of the wearer of the helmet. The frontal region 44 of the head engagement device may be arranged such that it can slide relative to the portion of the head ring to which it is adjacent, in the same manner as other sections of the head engagement device 40 are arranged to be able to move relative to other sections of the head mount, such as straps 20 where used.

The frontal region 44 of the head engagement device may be connected to the head ring and/or to the outer shell 2, for example by connectors that are configured to permit movement of one part relative to another, enabling movement of the frontal region 44 of the head engagement device 40 relative to the head ring 30. Alternatively or additionally, the frontal region 44 of the head engagement device 40 may be connected to the helmet 1 by way of an intermediate region 48 of the head engagement device 40. In particular, the intermediate region 48 of the head engagement device 40 may connect the frontal region 44 to the crown region 43. In an arrangement, the crown region 43, intermediate region 48 and frontal region 44 of the head engagement device may be integrally formed from a single plate of material.

As depicted in FIG. 7 , in an arrangement the frontal region 44 of the head engagement device 40 may extend along the head ring 30, for example in the form of arms 49. Each arm 49 of the head engagement device may therefore be adjacent but not conjoined to a side of the crown region 43 of the head engagement device. In an optional arrangement, one or more reinforcements may be provided between an or each arm 49 of the head engagement device 40 and an adjacent part of the crown region 43 of the head engagement device. This may be provided in order to reduce the extent to which the gap between the crown region 43 and the arm 49 of the head engagement device 40 increases under an impact on the helmet,

The reinforcements between the crown region 43 and the arm 49 of the head engagement device 40 may be integrally formed with the remainder of the head engagement device. Alternatively or additionally, a reinforcement may be provided in the form of a plate of material, for example formed from any of the materials discussed above for forming the head engagement device, that is connected at respective ends to the crown region 43 and the arm 49 of the head engagement device 40. The plate of material may be connected to the crown region 43 and the arm 49 of the head engagement device 40 by any convenient means, including for example, a hook and loop connection, a snap-fit connection and/or adhesive. The connectors may be adjustable such that a plate of material can be used as a reinforcement for different sizes of helmet.

The intermediate region 48 of the head engagement device may be configured such that it performs an additional function beyond connecting the crown region 43 to the frontal region 44. In particular, in the event of an impact towards the front of the helmet 1, the intermediate region 48 may assist in preventing the forehead of a wearer of the helmet from contacting the frontal region of the outer shell 2. For example, this may reduce the tendency for the front of the head of the wearer to pass between two straps 20 in an arrangement such as that depicted in FIG. 7 .

It should be appreciated that such an arrangement is not essential. The straps 20 used to form a head mount may be positioned to avoid such a potential problem in any event. For example, with a sufficient number of straps 20, and/or with sufficiently wide straps, the problem may be avoided or minimised. Alternatively or additionally a strap 20 may be provided that extends from the front of the helmet.

Alternatively or additionally, an additional support for the head engagement device may be provided that may ameliorate any tendency for the head of the wearer, and therefore the head engagement device, to pass through the gap between two straps and/or the head ring. Such a support may be provided in the form of a plate of material, for example formed from any of the materials discussed above for forming the head engagement device. The support may be connected to the head ring at a location between two straps. Such a support may, for example, be provided at one or more of either side of the helmet, the front of the helmet and the back of the helmet. The support may be connected to the head ring by any convenient means, including for example, a hook and loop connection, a snap-fit connection and/or adhesive.

In an arrangement, as depicted in FIG. 13 , although the crown region 43 of the head engagement device 40 is provided on the side of the head mount, such as straps 20, that faces the head of the wearer of the helmet 1, the frontal region 48 may be provided on the opposite side of the head ring 30. Accordingly, such an arrangement may be configured such that the head ring 30 is positioned between the forehead of the wearer of the helmet and the frontal region 48 of the head engagement device.

Such an arrangement may be beneficial if the head ring 30, at least in the region of the forehead, is relatively soft and/or flexible. In such an arrangement, the low friction interface between the frontal region 48 of the head engagement device 40 and the part of the head ring 30 adjacent the wearer's forehead will enable movement of the head ring 30, and therefore the forehead of the wearer, relative to the front region of the outer shell 2. As shown, the frontal region 48 of the head engagement device 40 may be connected to the head ring 30 by connectors 49. Such connectors may be similar to those discussed above or another suitable form of connector that permits relative movement between the connected components.

As shown in FIGS. 14 and 15 , one or more pads 66, 67 may be provided to the helmet 1. For example, in a helmet of any of the configurations discussed above that includes a frontal region 44 of the head engagement device 40, a front pad 66 may be positioned to be adjacent the forehead of the wearer of the helmet. Depending on the configuration of the helmet 1, the front pad may be connected to one or more of the head ring 30, the frontal region 44 of the head engagement device 40 and the out shell 2.

For example, the front pad 66 may be directly connected to the frontal region 44 of the head engagement device 40 in an arrangement in which the frontal region 44 of the head engagement device 40 is provided between the head ring 30 and the forehead of the wearer of the helmet. In such an arrangement, the frontal region of 44 of the head engagement device 40 may include projections or hooks 68 that may engage with the front pad 66.

Alternatively or additionally, the front pad 66 may be connected to the head ring 30 by way of elastic connectors 69 that engage with hooks or projections 70 formed on the head ring 30. In such a configuration, the elastic connectors 69 are configured to be able to stretch sufficiently that the front pad 66 is able to move relative to the head ring 30.

Alternatively or additionally, the front pad 66 may include a section of fabric, that optionally is elastically deformable, that extends outward and around the opposite side of the head ring 30. The front pad 66 may then be connected to the head ring, for example by a hook and loop connection with sections of hook or loop material, respectively, provided to the fabric extension of the front pad 66 and adhered to the surface of the head ring 30. Alternatively, the fabric extension of the front pad 66 may include elastic connectors that engage with hooks or projections formed on the head ring 30.

Arrangements with a fabric extension of the front pad 66 extending to the opposite side of the head ring may be preferred because it may have an improved aesthetic appearance and the fabric covering of the edges of the head ring and the head engagement device may reduce the risk of chafing of the helmet wearer's skin against the edges. Furthermore, when the head engagement device 40 moves relative to the head ring under an impact, a section of the head 30 ring may no longer be covered by the head engagement device. However, the fabric may slide relative to the head ring 30, enabling further movement to be provided.

In an arrangement such as that depicted in FIG. 13 , in which part of the head ring 30 is provided between the forehead of the wearer of the helmet and the frontal region 48 of the head engagement device 40, the front pad may be connected directly to the head ring 30. Alternatively or additionally, it may be connected by elastic connectors to the outer shell 2 and/or the frontal region 48 of the head engagement device 40.

In an arrangement, one or more pads 67 may be provided on other parts of the head engagement device 40, for example on a crown region 43 of the head engagement device 40. Such pads 67 may function to improve the comfort for the wearer of the helmet and/or to provide separation of the head engagement device 40 from the head of the wearer, promoting ventilation. As shown in FIG. 14 , the pads 67 may be positioned such that they do not overlap locations at which connectors 45 are provided, for example, to connect the head engagement device 40 to the head mount. Alternatively or additionally, one or more pads 67 may be positioned to cover the connectors 45.

As shown in FIG. 14 , one or more holes 43 may be provided in the head engagement device 40. Such holes may promote ventilation between the head of the wearer and the gap 21 between the head mount 20 and the outer shell 2.

As discussed above, the head engagement device 40 may also include one or more holes 41 used to engage with connectors. It should be appreciated that the head engagement device 40 may therefore be provided with holes that may function either to provide ventilation or to engage with a connector. Alternatively, different holes may be provided for specific functions.

It should also be appreciated that, where holes 41 are provided for engagement with connectors, a head engagement device 40 may be provided with holes 41 in the locations necessary for engagement with the connectors to fit the head engagement device 40 within a specific design of helmet. Alternatively, the head engagement device 40 may be provided with a plurality of holes 41 positioned to enable the engagement device 40 to be installed in any of a plurality of helmet designs and/or helmet sizes. 

1. A helmet, comprising: an outer shell; a head mount, configured to be mounted on the top of the head of a wearer of the helmet; wherein the head mount is suspended within the outer shell such that, in use, an air gap is provided between head mount and the outer shell; the helmet further comprises a head engagement device that is mounted on a surface of the head mount, that is configured to face the head of a wearer of the helmet, such that the head engagement device can move relative to the head mount; and a low friction interface is provided between the head mount and the head engagement device.
 2. A helmet according to claim 1, wherein the head engagement device is connected to the head mount.
 3. A helmet according to claim 1, wherein the head mount comprises a plurality of straps that are configured to extend across the top of the head of a wearer of the helmet and are connected to connection points on the outer shell.
 4. A helmet according to claim 3, wherein the head mount comprises a plurality of straps that extend between an opposing pair of connection points.
 5. A helmet according to claim 3, wherein at least two straps are connected to each other.
 6. A helmet according to claim 3, wherein the head engagement device is connected to the head mount by at least one connector that engages with one of the straps.
 7. A helmet according to claim 6, wherein the at least one connector has a first end and a second end that are both joined to the head engagement device at respective first and second locations on the head engagement device; and a strap is located between the connector and the head engagement device in a region between the first and second locations on the head engagement device.
 8. A helmet according to claim 6, wherein the strap is not fixedly secured to any part of the connector such that the strap can slide relative to the connector.
 9. A helmet according to claim 7, wherein the connector is formed from an elongate section of material, optionally one of a cord, band or a tape.
 10. A helmet according to claim 9, wherein plural connectors are formed from separate pieces of said material.
 11. A helmet according to claim 9, wherein plural connectors are formed from sections of a single piece of said material.
 12. A helmet according to claim 3, wherein the head mount comprises at least one strap connected to the front of the outer shell extending in a direction towards the rear of the helmet.
 13. A helmet according to claim 1, wherein the head engagement device is provided as a single component.
 14. A helmet according to claim 1, wherein the head engagement device is formed from plural separate sections.
 15. A helmet according to claim 1, wherein the head mount comprises a head ring that is configured to engage at least the forehead of a wearer of the helmet; and the head engagement device comprises a crown region that is configured to be located between the top of the head of a wearer of the helmet and the head mount, and a frontal region that is configured to be located adjacent the head ring.
 16. A helmet according to claim 15, wherein the head engagement device further comprises an intermediate region that connects the crown region to the frontal region.
 17. A helmet according to claim 15, wherein the frontal regional of the head engagement device is located between the forehead of the wearer of the helmet and the head ring.
 18. A helmet according to claim 15, wherein the head ring is located between the forehead of the wearer of the helmet and the frontal regional of the head engagement device.
 19. A helmet according to claim 15, further comprising a front pad positioned to be adjacent the forehead of the wearer of the helmet.
 20. A helmet according to claim 19, wherein the front pad is connected to at least one of the head ring, the frontal region of the head engagement device and the outer shell.
 21. A helmet according to claim 20, wherein the front pad is connected by elastic connectors that are configured to enable the front pad to move relative to the component to which it is connected.
 22. A helmet according to claim 1, wherein the head engagement device comprises one or more pads provided on a surface of the head engagement device facing the head of a wearer of the helmet.
 23. A helmet according to claim 1, wherein the head engagement device comprises a plate of material, optionally shaped to conform to the head of a wearer of the helmet.
 24. A helmet according to claim 23, wherein the head engagement device comprises a plurality of holes that may be configured to provide at least one of a location for a connector to join to the head engagement device and ventilation.
 25. A helmet according to claim 1, wherein the low friction interface is provided by a low coefficient of friction between the surfaces of the head mount and the head engagement.
 26. A helmet according to claim 1, wherein, in the absence of an impact on the helmet, the separation between the outer shell and the head mount at a location corresponding to the top of the head of a wearer provided by the air gap is at least 10 mm, optionally at least 15 mm, optionally at least 20 mm, optionally at least 30 mm, optionally at least 40 mm. 